Active polymer modification of bitumen for use in roofing materials

ABSTRACT

A modified bitumen consisting of a polyurethane wherein the polyisocyanate or polyisocyanate-dominated polyurethane prepolymer (or prepolymers) is first reacted with the bitumen to take advantage of the bitumen&#39;s hydroxyl and amine functionality and form an isocyanate-bitumen adduct to form a weatherproofing product.

The present invention is a continuation of U.S. patent application Ser.No. 14/624,672 filed Feb. 18, 2015, which in turn claims priority onU.S. Provisional Application Ser. No. 61/944,687 filed Feb. 26, 2014,which is incorporated herein by reference.

The present invention is directed to modified bitumen, more particularlyto a modified bitumen that includes a polyurethane, still moreparticularly to a modified bitumen that includes a polyurethane whereina polyisocyanate-terminated compound of any polymer backbone, or blendsof backbones, can be reacted with specific constituents of bitumen totake advantage of hydroxyl and amine functionality within saidconstituents and form an isocyanate-bitumen adduct, yet moreparticularly to a modified bitumen that includes a polyurethane whereinthe polyisocyanate-terminated compound of any polymer backbone, orblends of backbones, can be reacted with specific constituents ofbitumen to take advantage of hydroxyl and amine functionality withinsaid constituents and form an isocyanate-bitumen adduct and theremaining isocyanate groups on the adduct as well as any residualdiisocyanate not reacted with the bitumen are reacted further withpolyol(s), and still yet more particularly to a modified bitumen thatincludes a polyurethane wherein the polyisocyanate-terminated compoundof any polymer backbone can be reacted with specific constituents ofbitumen to take advantage of hydroxyl and amine functionality withinsaid constituents and form an isocyanate-bitumen adduct as well as anyresidual diisocyanate not reacted with the bitumen are reacted furtherwith polyol(s) to form a weatherproofing product (e.g., membrane, etc.).

BACKGROUND OF THE INVENTION

Bitumen is produced by the non-destructive distillation of crudepetroleum during the refining process, making the exact composition ofasphalt dependent on the chemical complexity of the original crudepetroleum. Asphalt is a blend of bitumen and mineral substances but,within the scope of this invention, bitumen also encompasses asphalt.While no two bitumen specimens have the same chemical makeup, itscomposition can be divided into four main designations through analyticmethods: saturates, aromatics, resins, and asphaltenes (otherwise knownas SARA's). Bitumen behavior is greatly influenced by the relativeconcentration and chemical features of these four phases, especiallythat of asphaltene, the most polar of the phases. The asphaltenemolecular structure has been measured over the decades and the findingis that the structure contains known hydroxyl (—OH) and amine (—NH)pendant groups. It is believed that under the right reaction conditions,these groups could be made to react with either monomeric and/orpolymeric polyisocyanate and/or a prepolymer consisting of one or morepolyester, polyether, hydroxyl-terminated polybutadiene, polycarbonate,and/or any imaginable hydroxyl-functional (functionality 2 or more) andpolyisocyanate (e.g., see the polyisocyanate and polyol listing that canbe used in U.S. Pat. No. 8,419,872, which is incorporated herein byreference). The reaction would create a bitumen/polyisocyanate adductthat can further react with —OH functional polyols of any molecularweight and/or any blend of functionality to improve the aforementionedphysical properties of the asphaltic membranes.

SUMMARY OF THE INVENTION

The present invention is directed to the combining of two knownwaterproofing compounds: asphalt and polyurethane, wherein theasphaltene groups become an “active” component within the polyurethanematrix rather than a “passive” component when blended with SBS or otherrubber used in the current art. Such a compound has been found to haveimproved weathering capabilities, mineral retention (SBS-modifiedbitumen can lose mineral surfacing when it ages), and more control overthe polymer creation and thus overall properties.

The non-limiting reasons for incorporation of polyurethane into asphaltand/or a rubber-modified asphaltic roof membrane are:

-   -   Improved Mineral Adhesion and Retention—The mineral granules        used in traditional rubber-modified asphalt formulations tend to        remove themselves from the modified surface during long term        exterior exposure, resulting in darker areas of exposed modified        asphalt that will degrade faster over time. The        urethane-modified bitumen of the present invention has shown        exceptional mineral retention (as much as 3-10 times the amount)        of roofing granules compared to the current art consisting of        rubber-modified bitumen.    -   Improved Weatherability—The urethane backbone of an        actively-modified polyurethane-based asphaltic material will        have better weathering properties depending on its composition        when compared to passively-modified rubber-based asphalt.        Consider, for example, the traditional SBS-modified asphalt used        in the current art. UV light and heat targets target specific        molecular groups within the rubber, making those bonds more        brittle, leading over time to cracking in the membrane. The        urethane-modified bitumen disclosed in this application has been        shown to have little or no surface cracking after 2400+ hours of        aging in a weathering machine or exterior exposure compared to a        modified bitumen specimen prepared by the current art.

Bitumen

The bitumen that can be used is non-limiting. Since the “reactive”component of this bitumen comes from the asphaltene and polar resins,the more asphaltene-rich colloidal microstructures in the bitumen, thelarger degree of active modification is obtained. An asphaltene weightfraction of about 10-25% is shown to be receptive to active modificationwith the prepolymers described, but it can be as high as about 50%. Theasphaltene weight fraction of the bitumen used in the present inventionis generally about 5-55% (and all values and ranges therebetween),typically about 7-45%, more typically about 10-30%. In one non-limitingexample, the bitumen is PG64-22 grade, which has about 15% asphaltenecontent (tested using an IATROSCAN—SARA Method). The more asphaltene ispresent, the more —OH and —NH reactive sites exist, and the morereactive sites are available for reaction with an —NCO group. In onenon-limiting embodiment, the bitumen or blend of bitumen (when used) hasa softening point about 43.3° C.-121.1° C. (110-250° F.) (and all valuesand ranges therebetween), typically, about 46.1° C.-76.7° C. (115°F.-170° F.), more typically about 47.8° C.-55.5° C. (118-132° F.); and apenetration typically of about 4-80 dmm (and all values and rangestherebetween) at 22.2° C. (75° F.), more typically about 25-75 dmm at22.2° C. (75° F.), still more typically about 40-75 dmm at 22.2° C. (75°F.), yet more typically about 51-69 dmm at 22.2° C. (75° F.), and stillyet more typically about 55-65 dmm at 22.2° C. (75° F.). The bitumen(when used) will be present in the composition in an amount of fromabout 25 wt. %-75 wt. % (and all values and ranges therebetween),typically from about 40%-60% wt. %.

Coal Tar

In non-limiting versions of this invention, coal tar can be used inplace of bitumen, or blends of coal tar and bitumen can be used. Thecoal tar that can be used is non-limiting. Coal tax pitch is a darkbrown to black amorphous residue left after coal tar is redistilled andis composed almost entirely of polynuclear aromatic compounds thatgenerally constitute 48-65% by weight of the usual grades of coal tar.The coal tar pitch useful in the compositions of the present inventionwill have a softening point of from about 50° C.−70° C. (and all valuesand ranges therebetween), and can be of either Type I or Type III.Typically, Type I coal tar pitches have a softening point of from around52° C. to 60° C., whereas Type III coal tar pitches have a softeningpoint of from around 56° C. to 64° C. The coal tar pitch will be presentin the composition in an amount of from about 25 wt. %-75 wt. % (and allvalues and ranges therebetween), and typically from about 50 wt. %-65wt. %. When coal tar and bitumen are both used, the weight ratio of coaltar to bitumen is about 1:0.01-99, and typically about 1:0.1-9. In onenon-limiting composition, the weight percent of the bitumen is greaterthan the weight percent of the coal tar; however, this is not required.In one non-limiting composition, the coal tar comprises from about 50wt. %-70 wt. % coal tar pitch, about 10 wt. %-17 wt. % rubbery polymerhaving from about 50-95 parts by weight conjugated diene and from about5-50 parts by weight monovinyl aromatics.

Polyisocyanate

The polyisocyanate compound can include aromatic, aliphatic,cycloaromatic and/or cycloaliphatic diisocyanates having molecularweights of up to about 500; however, higher molecular weights can beused. The —NCO functionality on the polyisocyanate (in the form ofmonomeric, polymeric, and/or prepolymeric) is what will react with the—OH and/or —NH pendant groups located on the asphaltene molecule.Hydroxyl (—OH) functional polyols are then reacted with the remainingunreacted monomeric, polymeric, and/or prepolymer —NCO pendant groups tofurther chain extend and crosslink the polymer. The prepolymer does notneed to be NCO functional; it can be —OH functional as well, but it willnot react with the —OH functional groups in the asphaltene and have verydifferent properties. NCO/OH equivalent indicies can be about 0.6-8, butgenerally about 1-6, and typically about 3-4.

Non-limiting examples of suitable aromatic diisocyanates include isomersof toluene diisocyanate (TDI), naphthalene 1,5-diisocyanate (NDI),naphthalene 1,4-diisocyanate (NDI), diphenylmethane 4,4′-diisocyanate(MDI), diphenylmethane 2,4′-diisocyanate and mixtures of4,4′-diphenylmethane diisocyanate with the 2,4′ isomer, xylylenediisocyanate (XDI), 4,4′-diphenyl-dimethylmethane diisocyanate, di- andtetraalkyl-diphenylmethane diisocyanates, 4,4′-dibenzyl diisocyanate,1,3-phenylene diisocyanate and 1,4-phenylene diisocyanate. Non-limitingexamples of cycloaliphatic diisocyanates include4,4′-dicyclohexylmethane diisocyanate (H₁₂MDI),1-isocyanatomethyl-3-isocyanato-1,5,5-trimethyl-cyclohexane (isophoronediisocyanate, IPDI), cyclohexane 1,4-diisocyanate, hydrogenated xylylenediisocyanate (H₆XDI), 1-methyl-2,4-diisocyanato-cyclohexane, m- orp-tetramethylxylene diisocyanate (m-TMXDI, p-TMXDI) and dimer fatty aciddiisocyanate. Non-limiting examples of aliphatic diisocyanates aretetramethoxybutane 1,4-diisocyanate, butane 1,4-diisocyanate, hexane1,6-diisocyanate (HDI), 1,6-diisocyanato-2,2,4-trimethylhexane,1,6-diisocyanato-2,4,4-trimethylhexane, lysine diisocyanate and1,12-dodecane diisocyanate (C₁₂CDI)_(y).

In another non-limiting embodiment of the invention, the one or morediisocyanate compounds include methylene diphenyl diisocyanate (MDI)and/or toluene diisocyanate (TDI). The MDI and/or TDI included in thepolyurethane prepolymer can be pure MDI and/or TDI, and/or one or moreisomers of MDI and/or TDI. As can be appreciated, almost any combinationof compounds that can be used to form the polyurethane prepolymer can beused in the present invention. As such, any combinations of polyol, orpolyols, with polyisocyanate, or polyisocyanates can be used in thepresent invention. The combination and type of compounds are selected toobtain the desired properties of the polyurethane. In one non-limitingaspect of this embodiment, MDI and/or TDI constitute at least about 40weight percent of the diisocyanate compounds in the polyurethaneprepolymer. In another non-limiting aspect of this embodiment, MDIand/or TDI constitute more than 50 weight percent of the diisocyanatecompounds in the polyurethane prepolymer. In still another non-limitingaspect of this embodiment, MDI and/or TDI constitute at least about 60weight percent of the diisocyanate compounds in the polyurethaneprepolymer. In yet another non-limiting aspect of this embodiment, MDIand/or TDI constitute at least about 75 weight percent of thediisocyanate compounds in the polyurethane prepolymer. In still yetanother non-limiting aspect of this embodiment, MDI and/or TDIconstitute at least about 90 weight percent of the diisocyanatecompounds in the polyurethane prepolymer. In a further non-limitingaspect of this embodiment, MDI and/or TDI constitute at least about 95weight percent of the diisocyanate compounds in the polyurethaneprepolymer. Non-limiting polyisocyanate compound that can be used isdisclosed in U.S. Pat. No. 8,419,872 patent, which is incorporatedherein by reference.

Polyols

One non-limiting goal of the polyol or polyol blends is to be used witha polyisocyanate (or polyisocyanates) to create polyurethane prepolymerthat can be later reacted with the bitumen. Another non-limiting goal ofthe polyol or polyol blends is to react completely or substantiallycompletely with the remaining available isocyanate (—NCO) groups. Theone or more primary polyol (two- and/or three-functional, referred to as“diols” and “triols”) compounds included in the polyurethane prepolymerand include a) polypropylene, and/or polybutylene glycols which caninclude di- and/or trifunctional polypropylene glycols with two or morehydroxyl groups per molecule in the molecular weight range of about400-20,000; b) polyether polyols wherein the molecular weight range isabout 200-4,000 molecular weight; c) hydroxyl-functional polybutadienepolyols wherein the molecular weight range is about 200-3000 molecularweight; d) polytetramethylene glycols (polybutylene glycols,poly(oxytetramethylene) glycol, poly-THF), wherein the molecular weightrange of the polytetramethylene glycols is about 600-6,000 molecularweight; e) low molecular weight polyols, alkylene diols (e.g.,butanediol, hexanediol, octanediol, decanediol, dodecanediol, etc.);and/or f) polyester-polyols such as the crystalline or partlycrystalline polyester-polyols which can be prepared by condensation ofdi- or tricarboxylic acids (e.g., adipic acid, sebacic acid, glutaricacid, azelaic acid, suberic acid, undecanedioic acid, dodecandioic acid,3,3-dimethylglutaric acid, terephthalic acid, isophthalic acid,hexahydrophthalic acid, polycaprolactone, etc.), dimer fatty acid withlow molecular weight diols or triols (e.g., ethylene glycol, propyleneglycol, diethylene glycol, triethylene glycol, dipropylene glycol,1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol,1,12-dodecanediol, dimer fatty alcohol, glycerol, trimethylolpropane,etc.).

Non-limiting examples of polyols that can be used include polypropyleneglycols (Diol) [e.g., PLURACOL® by BASF, etc.]; propylene oxide adductof glycerine (Triol) [e.g., PLURACOL® by BASF, etc.], polyether polyols(Diol & Triol) [e.g., VORANOL™ Polyols by Dow, ARCOL® Polyol by Bayer,ACCLAIM® Polyol by Bayer, ULTRACEL™ by Bayer, etc.]; hydroxyl functionalpolybutadiene polyols [e.g., POLY BD® and KRASOL®, from Cray Valley],polycarbonate diols [POLY-CD® 220 from Monument Chemical], polypropyleneoxide-based polyol (Diol) [e.g., MULTRANOL® by Bayer, etc.];1,12-octadecanediol; 1,2,3-propanetriol; 1,2,6-hexanetriol;1,2-ethanediol; 1,3-butanediol; 1,4-benzenediol; 1,9-nonanediol;2,2,4,4-tetramethyl-1,3-cyclobutanediol;2,2,4-trimethyl-1,3-pentanediol; 2,2-bis(hydroxymethyl)-1,3-propanediol;2,2-diethyl-1,3-propanediol; 2,2-dimethyl-1,3-butanediol;2,3-butanediol; 2,3-naphthalenediol; 2,4-hexadiyne-1,6-diol;2,7-dimethyl-3,5-octadiyne-2,7-diol; 2-butyl-2-ethyl-1,3-propanediol;2-ethyl-2-methyl-1,3-propanediol; 2-methyl-2-propyl-1,3-propanediol;3-chloro-1,2-propanediol; 3-methyl-1,3-butanediol;3-methyl-2,4-pentanediol; 9-octadecene-1,12-diol; actol 21-56 diol;actol 22-110 diol; actol 23-95 diol; actol 32-160 triol; actol 33-46triol; butanediol; butanetriol; butenediol; butynediol; dimethyloctanediol; and dimethylhexanediol.

Generally, the polyols are petroleum-based polyols, but they can also beproduced using soy, castor, or other so-called “green” sources. In onenon-limiting aspect of this embodiment, two different primary polyolcompounds are included in the polyurethane prepolymer. In onenon-limiting formulation, the primary polyol compounds include a firstprimary polyol compound that is a diol or triol polyol having amolecular weight that is at least about 300 and up to about 5000 and asecond primary polyol compound that is a diol or triol having amolecular weight of at least about 150 and up to about 7000. Generallythe first primary polyol compound is a diol and the second primarypolyol compound is a triol, but can also be a diol. The weight ratio ofthe higher weight primary polyol compound to the lower weight primarypolyol compound is about 1-5:1, typically about 1.1-4:1, and moretypically about 1.2-3.5:1. In another and/or alternative non-limitingaspect of this embodiment, the one or more primary polyol compoundsincluded in the polyurethane prepolymer includes diol and/or triol. Instill another non-limiting aspect of this embodiment, the diol and/ortriol constitute at least about 40 weight percent of the one or moreprimary polyol compounds in the polyurethane prepolymer. In yet anothernon-limiting aspect of this embodiment, the diol and/or triol constitutemore than 50 weight percent of the one or more primary polyol compoundsin the polyurethane prepolymer. In still another non-limiting aspect ofthis embodiment, the diol and/or triol constitute at least about 60weight percent of the one or more primary polyol compounds in thepolyurethane prepolymer. In still yet another non-limiting aspect ofthis embodiment, the diol and/or triol constitute at least about 75weight percent of the one or more primary polyol compounds in thepolyurethane prepolymer. In a further non-limiting aspect of thisembodiment, the diol and/or triol constitute at least about 90 weightpercent of the one or more primary polyol compounds in the polyurethaneprepolymer. In still a further non-limiting aspect of this embodiment,the diol and/or triol constitute at least about 95 weight percent of theone or more primary polyol compounds in the polyurethane prepolymer. Inanother non-limiting aspect of this embodiment, the one or more primarypolyol compounds included in the polyurethane prepolymer include bothdiol and triol.

In another non-limiting aspect of this embodiment, the polyol or polyolblend can include about 200-20000 molecular weight of one or more diols,triols, and/or quadrols, and the polyol or polyol blend can be added ina quantity to create an NCO/OH equivalent ratio of about 1.2-15.1.

In another non-limiting aspect of this embodiment, the polyol or polyolblend can include about 1000-5000 molecular weight of one or more diols,triols, and/or quadrols, and the polyol or polyol blend can be added ina quantity to create an NCO/OH equivalent ratio of about 1.2-15:1.

In another non-limiting aspect of this embodiment, the polyol or polyolblend can include about 1000-3000 molecular weight of one or more diols,triols, and/or quadrols, and the polyol or polyol blend can be added ina quantity to create an NCO/OH equivalent ratio of about 1.2-15:1.

In another non-limiting aspect of this embodiment, the polyol or polyolblend can include about 1800-2200 molecular weight polyethylene glycoldiol, and the polyol or polyol blend can be added in a quantity tocreate an NCO/OH equivalent ratio of about 1.2-15:1.

In still another non-limiting aspect of this embodiment, the one or moreprimary polyol compounds included in the polyurethane prepolymer includeboth diol and triol at a weight ratio of diol to triol of about 1-5:1,typically about 1.5-3:1, and more typically about 1.8-2.2:1. A weightratio of greater than 5:1 has been found to cause the cross-link densityto decrease, and eventually the tensile strength of the cured blend isnot affected by the triol. A ratio of less than 1:1 (by weight)increases the chance of the polymer approaching or exceeding its gelpoint.

In yet another non-limiting embodiment of the invention, the equivalentratio of the at least one polyisocyanate compound to the one or moreprimary polyol compounds in the polyurethane prepolymer is about1.2-8:1, typically about 2-7:1, more typically about 3-6:1, still moretypically about 4.5-5:1. In one non-limiting aspect of this embodiment,the polyurethane prepolymer includes at least about 5 weight percent ofat least one polyisocyanate compound and more than 50 weight percent ofone or more primary polyol compounds. In another non-limiting aspect ofthis embodiment, the polyurethane prepolymer includes about 10-30 weightpercent of at least one diisocyanate compound 60-90 weight percent ofone or more primary polyol compounds. In still another non-limitingaspect of this embodiment, the polyurethane prepolymer includes about12-25 weight percent of at least one diisocyanate compound 65-88 weightpercent of one or more primary polyol compounds. In yet anothernon-limiting aspect of this embodiment, the polyurethane prepolymerincludes about 15-20 weight percent of at least one diisocyanatecompound 70-85 weight percent of one or more primary polyol compounds.In still yet another non-limiting aspect of this embodiment, thepolyurethane prepolymer includes about 18-20 weight percent of at leastone diisocyanate compound 74-82 weight percent of one or more primarypolyol compounds.

In addition to the primary and secondary polyols, one could also use lowor high molecular weight polyols to be chain extenders and/orcrosslinkers used to join the much larger polymer chains to form evenlonger polymers. Such chain extenders and/or crosslinkers can include,but are not limited to, propylene glycol, ethylene glycol,1,3-butanediol, dipropylene glycol, and the like. Non-limiting polyolsthat can be used are disclosed in U.S. Pat. No. 8,419,872, which isincorporated herein by reference.

In one non-limiting composition, the combined weight percent ofpolyisocyanate and polyol used in the composition is generally about1-70 wt. % (and all values and ranges therebetween), typically about1-49 wt. %, more typically about 2-45 wt. %, still more typically about3-40 wt. %, yet more typically about 3-30 wt. %, still yet moretypically about 4-25 wt. %, even more typically about 7-20 wt. %, stilleven more typically about 10-17 wt. %, yet even more typically about13-17 wt. %.

In one non-limiting embodiment, the combined weight percent ofpolyisocyanate and polyol in the composition is generally less than thecombined weight percent of the bitumen and coal tar in the composition;however, this is not required. Generally the weight ratio of thecombined weight percent of polyisocyanate and polyol in the compositionto the combined weight percent of the bitumen and coal tar in thecomposition is about 0.05-0.7:1, typically about 0.1-0.5:1, and moretypically about 0.2-0.4:1.

In one non-limiting formulation, diisocyanate (e.g., Polymeric MDI,etc.) is reacted with a non-linear diol at about 1.5-5:1 equivalentratio, and then reacted further with about 1.1-3:1 equivalent blend of alinear diol and diol. A specific non-limiting formulation is 4,4′-MDI(diisocyanate) is reacted first with an about 1800-2200 molecular weighthydroxyl-functional polybutadiene (non-linear diol) at an about2.5-3.5:1 equivalent ratio, then reacted further with about 1.5-2.5:1equivalent blend of an about 1800-2200 molecular weight linearpolybutadiene (linear diol) and an about 1800-2200 molecular weightpolycarbonate diol (diol).

The blend of polyisocyanate compound and polyol prior to reacting withthe bitumen and/or coal tar (i.e., pre-reacted prepolymer) can includean extended NCO-terminated prepolymer having about a 1.2-15:1 ratio ofhydroxyl-terminated polybutadiene. The polyol or polyol blend caninclude one or more diols, triols, and/or quadrols, and the polyol orpolyol blend can be added in a quantity to create an NCO/OH equivalentratio of about 1.2-8:0.001-20. The pre-reacted prepolymer can be formedfrom an extended NCO-terminated prepolymer having about a 1-15:1 NCO/OHequivalent ratio consisting of about 200-20000 MW hydroxyl-terminatedpolybutadiene, and the polyol or polyol blend can include about200-20000 MW of one or more diols, triols, and/or quadrols, and thepolyol or polyol blend can be added in a quantity to create an NCO/OHequivalent ratio of 1.2-8:0.001-20. The pre-reacted prepolymer can beformed from an extended NCO-terminated prepolymer having about a1.2-15:1 ratio of 1000-5000 molecular weight hydroxyl-terminatedpolybutadiene, and the polyol or polyol blend can include about1000-5000 molecular weight of one or more diols, triols, and/orquadrols, and the polyol or polyol blend can be added in a quantity tocreate an NCO/OH equivalent ratio of 1.2-8:1. The pre-reacted prepolymercan be formed from an extended NCO-terminated prepolymer having about a1.2-15:1 ratio of about 1000-3000 molecular weight hydroxyl-terminatedpolybutadiene, and the polyol or polyol blend including about 1000-3000molecular weight of one or more diols, triols, and/or quadrols, saidpolyol or polyol blend can be added in a quantity to create an NCO/OHequivalent ratio of 1.2-8:1. The pre-reacted prepolymer can be formedfrom an extended NCO-terminated prepolymer having about a 1.2-15:1equivalent ratio of about 1800-2200 molecular weight hydroxyl-terminatedpolybutadiene, and the polyol or polyol blend including about 1800-2200MW polycarbonate diol, and the polyol or polyol blend can be added in aquantity to create an NCO/OH equivalent ratio of 1.2-8:1.

Filler

A filler can optionally be used. The filler can be one or more of any ofthe typical types of fillers used in the art. Non-limiting fillersinclude fire retardant, calcium carbonate, talc, ammonium polyphosphate,ATH (Alumina Trihydrate (Al₂O₃.3H₂O)) or Mg(OH)₂. The fillers can beused for fire retardancy, etc. Additional fillers are disclosed in U.S.Pat. No. 8,419,872, which is incorporated herein by reference. When afiller is used, the content of the filler is generally about 1-66 wt. %(and all values and ranges therebetween), typically about 30-41 wt. %,and more typically about 34-38 wt. %. One non-limiting filler that canbe used includes about 5-40 wt. % calcium carbonate (and all values andranges therebetween), about 0.5-20 wt. % ATH (and all values and rangestherebetween), and about 0.1-5 wt. % ammonium polyphosphate (and allvalues and ranges therebetween); and more typically about 20-30 wt. %calcium carbonate, about 5-15 wt. % ATH, and about 0.5-2 wt. % ammoniumpolyphosphate.

Rubber

A SBS (styrene-butadiene-styrene), SEBS (styrene ethylene butylenestyrene), SIS (styrene isoprene styrene), nitrile rubber, or any rubbercan be used in conjunction with the polyurethane prepolymer into theasphalt, but is not necessary. Additional rubbers are disclosed in U.S.Pat. No. 8,419,872, which is incorporated herein by reference. In onenon-limiting arrangement, the rubber (when used) can be blended with theurethane from about 1:0.1-99.9 by weight to rubber (and all values andranges therebetween), typically about 1:0.1-10 by weight urethane torubber, more typically about 1:0.2-15 by weight urethane to rubber,still more typically about 1:0.2-5 by weight urethane to rubber, andstill more typically about 1:0.3-3 by weight urethane to rubber. In onenon-limiting formulation, the urethane content is less than the rubbercontent. In another non-limiting formulation, the urethane content isgreater than the rubber content. In one non-limiting composition, therubber has a block monomer distribution in the form of A-B-A whereineach end block A is a polymer block of a polymerized monovinyl aromaticmonomer and the midblock B is a polymer block of polymerized diene. Theweight percent of the rubber (when used) can be about 1-30 wt. % (andall values and ranges therebetween), typically about 1-20 wt. %, moretypically about 1-10 wt. %, still more typically about 2-5 wt. %. In onenon-limiting composition, the weight percent of rubber is less than thecombined weight percent of the bitumen and coal tar; however, this isnot required.

Processing Oils

A non-limiting component of the invention uses a processing oil thatincludes virtually any hydrocarbon oil or mixture thereof that iscommonly used in bitumen and/or coal tar compounding or as a plasticizerand processing aid (such as a naphthelinic or paraffinic oil containingvarying aromatic contents) can be used, but is not necessary. Theextender should be compatible with the components of the formula.Specific, non-limiting examples of suitable extender oils include Sundex790T from Sunoco, ProGuard Altranap 1000 from Lynden Oil Co., andAmplex® 100 from Citgo. Additional processing oils are disclosed in U.S.Pat. No. 5,455,291, which is incorporated herein by reference. Theprocessing oil (when used) can be about 0.1-30 wt. % (and all values andranges therebetween), typically about 0.5-5 wt. %, and more typicallyabout 1-3 wt. %. In one non-limiting formulation, the coal tar and/orbitumen includes about 10-15 wt. % of an extender oil having an aromaticcontent such that the composition contains less than about 8 wt %aromatic oil exclusive of any aromatics resulting from the coal tarand/or bitumen.

Modifiers

A modifier can optionally be used. Non-limiting modifiers includecross-linkers that can be used to help increase cross link density(amines, for example), antioxidants, UV stabilizers to preventdegradation, etc. Additional modifiers are disclosed in U.S. Pat. No.8,419,872, which is incorporated herein by reference. The modifiers(when used) can about 0.01-5 wt. % (and all values and rangestherebetween), and typically about 0.1-1 wt. %.

Antioxidants

An antioxidant can optionally be used. There are typical ones in theindustry. The antioxidant can be used to further improve the stabilityof the composition. The antioxidants (when used) can be about 0.01-5 wt.% (and all values and ranges therebetween), and typically about 0.1-1wt. %. Non-limiting antioxidants include Irgonox® 1010 (BASF), CYASORB®UV stabilizers (Cytec).

Catalysts

A catalyst can optionally be used. One non-limiting catalyst isdibutyltin dilaurate. Additional catalysts are disclosed in U.S. Pat.No. 8,419,872, which is incorporated herein by reference. The additionof a catalyst can be used to control the reaction speed. Care needs tobe taken when using catalysts because of gellation risks. Generally, nomore than 1 wt. % is recommended (e.g., 0.01-1 wt. % and all values andranges therebetween). Non-limiting catalyst that can be used includes1,3,5-(tris(3-dimethylamino)propyl)-hexahydro-s-triazine,1,8-diazabicyclo[5,4,0]undecene-7 (DBU), 1,4-diazabicyclo[2,2,2]octane,tetramethylbutanediamine (TMBDA), benzyldimethylamine (BDMA),bis-(2-dimethylaminoethyl)ether, dibutyltin dilaurate, dibutyltin oxide,dimethylcyclohexylamine (DMCHA), dimethylethanolamine (DMEA), dioctyltinmercaptide, N-ethylmorpholine,N-(3-dimethylaminopropyl)-N,N-diisopropanolamine,N′-(3-(dimethylamino)propyl)-N,N-dimethyl-1,3-propanediamine,N,N,N′-trimethyl-N′-hydroxyethyl-bis(aminoethyl)ether,pentamethyldiethylenetriamine (PMDETA), pentamethyldipropylenetriamine,phenylmercuric neodeconate, tin mercaptides, triethylamine (TEA),triethylenediamine (TEDA).

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a graph that illustrates the effect if aged UV exposure onpeak strength of conventional rubber-modified bitumen to the urethanemodified formulation of the present invention; and,

FIG. 2 is a graph illustrating the amount of mineral loss of aconventional mineral cap sheet to a sheet that includes the urethanemodified formulation of the present invention.

NON-LIMITING FORMULATIONS

One non-limiting formula of the present invention comprises bitumenand/or coal tar, polymer and optional filler. The polymer can be anyblend of polyisocyanate/polyol or polyols and/or styrenated rubber orrubbers from about 1-25 wt. % loading. Generally, about 8-20 wt. % totalpolymer loading by weight of total formula is used. Polyol order ofaddition with respect to the diisocyanate is important. The polyols canbe blended in any order with respect to the polyisocyanate, withdifferent results expected with each different order of addition. Thebitumen and/or coal tar is actively modified by reacting the isocyanateend groups in the polyurethane with the hydroxyl end groups found in thebitumen and/or coal tar. As such, the polyurethane can have isocyanatefunctionality; however, this is not required. Each of these formulaexamples was compared to a control representing what could be consideredthe current art consisting of the following composition:

Control—Typical SBS-Modified Formula

Component Weight Percent Bitumen 50% Lineal SBS Rubber 15% Filler 35%Formula 1:

Component Weight Percent Bitumen 30-70% Diisocyanate (monomeric,  4-20%polymeric, prepolymeric Polyol (diol, triol, diol/diol blend, diol/triolblend, etc.) Filler (includes any calcium 10-66% carbonate, fireretardants, etc.)

Example 1—Based on Formula 1

Component Component Weight Percent PG 64-22 (or other Bitumen 50-55%bitumen) Rubinate 9433 4,4-MDI  8-20% R45HTLO Hydroxy-terminatedpolybutadiene Krasol LBH 2000 Linear Hydroxy- terminated polybutadienePoly CD220 2000 MW Polycarbonate diol CaCO₃, Aluminum Filler, Flame30-41% trihydrate (ATH), retardant Potassium polyphosphate

Example 2—Based on Formula 1

Component Component Weight Percent PG 64-22 (or other Bitumen 50-55%bitumen) Hyperlast LP 5610 Linear  8-20% butadiene/MDI baseddiisocyanate terminated prepolymer R45HTLO Hydroxy-terminatedpolybutadiene Poly CD220 2000 MW Polycarbonate diol CaCO₃, AluminumFiller, Flame 30-41% trihydrate (ATH), retardant Potassium polyphosphate

One non-limiting method for creating the composition of Formula 1 andExample 1 is to add the monomeric, polymeric, or prepolymericdiisocyanate to the molten bitumen or a blend of bitumen and fillers ata process temperature of about 160-179.4° C. (320-355° F.) for about10-60 minutes (e.g., 25-35 min., etc.). Then, after determination ofresidual % NCO using potentiometric titration or other method familiarto those skilled in the art, enough polyol is added to react with theremaining isocyanate pendant groups. The blend of polyols will helpdetermine the physical properties of the final product, so choice ofblend is important. Another non-limiting method for creating thecomposition of Formula 1 and Example 1 is to first extend theprepolymeric diisocyanate further using processes familiar to those inthe art with additional polyol or polyol blends such that the extendedprepolymer increases in molecular weight, but still maintains some NCOfunctionality, but said NCO functionality is lower than the initialprepolymer's NCO content. Said extended NCO-dominated prepolymer is thenadded to molten bitumen or a blend of molten bitumen and fillers at160-179.4° C. (320-355° F.). After allowing the reaction of theNCO-terminated prepolymer and hydroxyl pendant groups of the asphaltinemolecules within the bitumen, titration can be used to determine if anyresidual —NCO exists, which in turn can be used to calculate theequivalents of an optional amount of chain extender or other polyoland/or amine structure to increase viscosity, but is not necessary.

FORMULA 2: Active Modification of SBS-Modified Asphalt

Component Weight Percent Bitumen 50-55% Rubber (SBS, SEBS, SIS, 4-20%Loading Total at and blends thereof) Various Ratios Diisocyanate(monomeric, polymeric, or prepolymeric) Polyol (diol, triol, diol/triolblend) Filler 10-66% Process Oil  1-5%

Example 3—Based in Formula 2

Component Component Weight Percent PG 64-22 Bitumen 50-55% SBS, SIS,SEBS (or Rubber In various weight blends thereof) ratios such that thePolymeric MDI NCO-terminated overall weight % is polymeric less than orequal to diisocayante 20% PPG 2000 2000 MW polyol Voranol 220-530 500 MWdiol CaCO₃, Aluminum Filler, flame 30-41% trihydrate, Ammonium retardantpolyphosphate Naphthenic process oil Process oil  1-3%

One non-limiting method for creating the composition of Formula 2 andExample 3 is to first blend the SBS, SIS, and/or SEBS or blend thereofinto molten asphalt, followed by the fillers. Once the rubber/asphaltblend is fully associated, the polymeric diisocyanate follows, but theprepolymer can be extended ahead of time with a polyol blend, but is notnecessary. Reaction temperature should remain between 160-179.4° C.(320-355° F.); higher temperature increases the risk of gelation.

Table 1 shows physical properties observed in modified bitumen roofingmembranes made with the aforementioned formulations compared to acontrol produced using conventional processes.

TABLE 1 Physical Properties Observed With Invention vs. ControlComponent Control Example 1 Example 2 Example 3 Softening Point 272° F.400° F. 400° F. 290° F. (ASTM D3461, ° F.) Penetration 20 dmm 21 dmm 31dmm 22 dmm (ASTM D5, Units) Compound Stability Pass 225° F. Pass 225° F.Pass 225° F. Pass 220° F. (ASTM D5147) Granule Loss (%, Dry, 4% 0.7%  0.9%   2% ASTM D4977) Aged Appearance Some cracking, No cracking, Nocracking, No cracking, 4000 hours in Q-Sun shrinkage, sagging.shrinkage, shrinkage, shrinkage, Weathering Some blisters sagging,sagging, sagging, blisters blisters blisters Low Temperature Pass −50°F. Pass −10° F. Pass −20° F. Pass −30° F. Flexibility Granule Loss after6% 1% 1% DNT 4000 h Exposed in Georgia (%, Dry, ASTM D4977) Granule Lossafter 7% 1% 1% DNT 4000 h Exposed in California (%, Dry, ASTM D4977)DNT: Did not test

Table 1 shows that for the membrane made using Example 1, wherein onlypolyurethane comprised the total polymer content, the softening pointincreased to 400° F., which translates to improved high temperature sagresistance. In fact, even when exposed to 300° F., the membrane madewith Example 1 did not show any signs of sag or mineral loss, while thecontrol softened to the point where flow occurred. However, the membraneretained its flexibility at low temperature. The mineral roofingmembrane created with Example 3 had properties closer to that of theControl. This is to be expected as the asphalt will take on propertiesof both polymers.

ASTM D412 Stress-Strain Testing of QUV-Aged Films

To demonstrate the resistance to aging of the invention made by theExamples (specifically Example 1), films of just the modified bitumenwere placed into a QUV chamber for 3000+ hours and tested at 500 hourintervals to determine peak stress values. At these intervals, 1″ widestrips were cut and pulled on a tensile tester until failure. FIG. 1shows the results.

The data in FIG. 1 shows that prior to 2000 hours there is a steadyincrease in strength which occurs as a result of UV-induced crosslinkingreactions that can occur in both traditional rubber and urethanes.Significantly, beyond 2000 hours there is a 13% decrease in strength inthe urethane compared to a nearly 40% decrease in strength with theconventional modified bitumen as the films are continually exposed inthe intense UV-rich environment. This trend continues with little changeto 3000 hours.

ASTM 4977 Scrub Testing—Mineral Loss

The mineral retention properties of the membrane made by the Examples(specifically Example 1), show significant improvement over theconventionally produced roofing membrane. When the substrates were agedover 4000 hours in California and Georgia, mineral retention in Example1 was 6-7 times better than the conventional roofing membrane. Tofurther test the invention's mineral retention, specimens of mineralroofing membranes made with Example 1 were soaked for 72 hours in water,and then a granule loss test was performed on the wet aged samplesalongside a control similarly conditioned. The results are shown in FIG.2.

Wet vs. Dry Scrub Test Results

Wet scrub testing was not performed on Example 2. The data in FIG. 2clearly shows that Example 1 has an eight-fold improvement in mineralretention vs. the conventional mineral cap sheet. When tested dry,Examples 1 and 2 still show a three-fold improvement in mineral loss.

ASTM D4798 Cycle A-1 Weathering

As a demonstration of the improved weatherability of the invention,environmental aging was performed in a Q-Sun Model XE-3-HS (Q-Lab).Exposures of the non-limiting examples of the invention verses asimilarly prepared convention mineral cap sheet show that, after morethan 4000 hours subjected to ASTM D4798 Cycle A-1, wherein the preparedpanels were subjected to a continuous hourly cycle consisting of a51-minute light only exposure of “noon day sun” at 60° C. atequilibrium, followed immediately by a 9-minute period of light/waterspray, Examples 1 and 2 show no signs of blistering or surface defects,while the conventional mineral cap sheet had begun to show signs ofsmall blisters on the surface.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained, andsince certain changes may be made in the constructions set forth withoutdeparting from the spirit and scope of the invention, it is intendedthat all matter contained in the above description and shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense. The invention has been described with reference topreferred and alternate embodiments. Modifications and alterations willbecome apparent to those skilled in the art upon reading andunderstanding the detailed discussion of the invention provided herein.This invention is intended to include all such modifications andalterations insofar as they come within the scope of the presentinvention. It is also to be understood that the following claims areintended to cover all of the generic and specific features of theinvention herein described and all statements of the scope of theinvention, which, as a matter of language, might be said to falltherebetween.

What is claimed:
 1. An actively modified polymer-modified bitumenformulation comprising: 25-75 wt. % of a first component that consistsof bitumen, coal tar, or combinations thereof; 1-49 wt. % of a secondcomponent that consists of polyurethane, or blend of polyurethane andrubber, said polyurethane including isocyanate end groups, saidpolyurethane formed from a polyisocyanate compound and a polyol, saidpolyol includes a molecular weight compound of 1000-5000 molecularweight, a content of said polyol creating a NCO/OH equivalent ratio of2:1 to 7:1 in said bitumen formulation; and, 1-66 wt. % of a filler;wherein a weight percent of said first component is greater than aweight percent of said second component, said isocyanate end groups insaid polyurethane formulated to be reactable with hydroxyl end groups insaid bitumen, said coal tar, or combinations thereof, said formulationcan be used to create a membrane having improved mineral retention andweatherability.
 2. The formulation as defined in claim 1, wherein saidpolyol includes at least one compound selected from the group consistingof propylene glycol, polycarbonate diol, polybutadiene glycols andpolybutadiene polyols.
 3. The formulation as defined in claim 1, whereinsaid polyol includes at least two compounds selected from the groupconsisting of propylene glycol, polycarbonate diol, polybutadieneglycols and polybutadiene polyols.
 4. The formulation as defined inclaim 1, wherein said polyol includes at least three compounds selectedfrom the group consisting of propylene glycol, polycarbonate diol,polybutadiene glycols and polybutadiene polyols.
 5. The formulation asdefined in claim 3, wherein said polyol includes two different types ofcompounds selected from the group consisting of propylene glycol andpolycarbonate diol.
 6. The formulation as defined in claim 4, whereinsaid polyol includes two different types of compounds selected from thegroup consisting of propylene glycol and polycarbonate diol.
 7. Theformulation as defined in claim 1, wherein said NCO/OH equivalent ratiois 3:1 to 6:1.
 8. The formulation as defined in claim 1, wherein saidfiller includes at least one compound selected from the group consistingof potassium polyphosphate, calcium carbonate, ammonium polyphosphate,alumina trihydrate and Mg(OH)₂.
 9. The formulation as defined in claim8, wherein said filler includes three or more compounds selected fromthe group consisting of calcium carbonate, ammonium polyphosphate,alumina trihydrate and potassium polyphosphate.
 10. The formulation asdefined in claim 8, wherein said filler includes calcium carbonate,ammonium polyphosphate, and alumina trihydrate.
 11. The formulation asdefined in claim 8, wherein said filler includes calcium carbonate,ammonium polyphosphate, and alumina trihydrate, a content of saidcalcium carbonate is 5-40 wt. %, a content of said ammoniumpolyphosphate is 0.1-5 wt. %, a content of said alumina trihydrate is0.5-20 wt. %.
 12. The formulation as defined in claim 1, wherein saidsecond component includes both said polyurethane and said rubber, saidrubber including one or more compounds selected from the groupconsisting of SBS, SEBS, SIS, and nitrile rubber, a weight ratio of saidrubber to said polyurethane is 1:0.2 to 1:15.
 13. The formulation asdefined in claim 1, wherein said first component includes a blend ofsaid coal tar and said bitumen, a weight ratio of said coal tar and saidbitumen 1:0.1 to 1:10.
 14. The formulation as defined in claim 1,further including two or more additional components selected from thegroup consisting of processing oil, chain extender, modifier,antioxidant, and catalyst, said additional components having a weightpercent of 10-66.
 15. The formulation as defined in claim 1, whereinsaid polyol includes both diols and triols, a weight ratio of said diolsto said triols is about 1:1 to 5:1.
 16. The formulation as defined inclaim 1, wherein said polyurethane includes at least one chain extender.17. The formulation as defined in claim 1, wherein said chain extenderincludes one or more compounds selected from the group consisting ofpropylene glycol, ethylene glycol, 1,3-butanediol, and dipropyleneglycol.
 18. The formulation as defined in claim 1, wherein said polyolincludes a molecular weight compound of 1000-3000.
 19. The formulationas defined in claim 1, comprising by weight percent: Bitumen and/or coaltar 30-70 Polyurethane   4-20% Filler  10-66.


20. The formulation as defined in claim 1, comprising by weight percent:Bitumen and/or coal tar 50-55 Polyurethane  8-20 Filler 30-41.


21. The formulation as defined in claim 1, comprising by weight percent:Bitumen and/or coal tar 50-55 Polyurethane  8-20 Filler 30-41 Processoil  1-5.


22. The formulation as defined in claim 1, comprising by weight percent:Bitumen and/or coal tar 50-55 Polyurethane  8-20 Filler 30-41 Processoil  1-3.


23. The formulation as defined in claim 1, comprising by weight percent:Bitumen and/or coal tar 25-75  Polyurethane 2-49 Filler 1-66 Process Oil1-20 Rubber 1-30 Modifier 0.01-5    Antioxidant 0.01-5    Catalyst0.01-1.  


24. The formulation as defined in claim 1, comprising by weight percent:Bitumen 50-55 Calcium Carbonate  5-40 Aluminum Trihydrate 0.5-20 Ammonium Polyphosphate 0.1-5   Polyurethane   8-20.


25. An actively modified polymer-modified bitumen formulationcomprising: 30-70 wt. % of a first component that consists of bitumen,coal tar, or combinations thereof; 4-20 wt. % of a second component thatconsists of polyurethane, or blend of polyurethane and rubber, saidpolyurethane including isocyanate end groups, said polyurethane formedfrom a polyisocyanate compound and a polyol, said polyol includes amolecular weight compound of 1000-5000 molecular weight, said polyolincludes at least two compounds selected from the group consisting ofpropylene glycol, polycarbonate diol, polybutadiene glycols andpolybutadiene polyols, a content of said polyol creating a NCO/OHequivalent ratio of at least 2:1 and no greater than 15:1 in saidbitumen formulation; and, 10-66 wt. % of a filler; wherein a weightpercent of said first component is greater than a weight percent of saidsecond component, a weight ratio of said polyisocyanate and said polyolto said first component is 0.1:1 to 0.5:1, said isocyanate end groups insaid polyurethane formulated to be reactable with hydroxyl end groups insaid bitumen, said coal tar, or combinations thereof, said formulationcan be used to create a membrane having improved mineral retention andweatherability.
 26. The formulation as defined in claim 25, wherein saidpolyol includes both diols and triols, a weight ratio of said diols tosaid triols is about 1:1 to 5:1.
 27. The formulation as defined in claim26, comprising by weight percent: Bitumen  50-55 Calcium Carbonate  5-40 Aluminum Trihydrate 0.5-20 Ammonium Polyphosphate 0.1-5Polyurethane   8-20.


28. An actively modified polymer-modified bitumen formulationcomprising: 40-60 wt. % of a first component that consists of bitumen,coal tar, or combinations thereof; 4-20 wt. % of a second component thatis formed of a polyurethane material, said polyurethane materialincluding isocyanate end groups, said polyurethane material formed froma polyisocyanate compound and a polyol, said polyol includes a molecularweight compound of 1000-5000 molecular weight, said polyol includes atleast two compounds selected from the group consisting of dipropyleneglycol, propylene glycol, polycarbonate diol, polybutadiene glycol andpolybutadiene polyol, a content of said polyol creating a NCO/OHequivalent ratio of at least 2:1 and no greater than 15:1 in saidbitumen formulation; wherein a weight percent of said first component isgreater than a weight percent of said second component, a weight ratioof said polyisocyanate, and said polyol to said first component is 0.1:1to 0.5:1, said isocyanate end groups in said polyurethane formulated tobe reactable with hydroxyl end groups in said bitumen, said coal tar, orcombinations thereof, said formulation formulated to create a membranehaving improved mineral retention and weatherability.
 29. Theformulation as defined in claim 28, wherein said polyol includes atleast three compounds selected from the group consisting of dipropyleneglycol, propylene glycol, polycarbonate diol, polybutadiene glycol, andpolybutadiene polyol.
 30. The formulation as defined in claim 28,wherein said polyol includes at least two compounds selected from thegroup consisting of hydroxy-terminated polybutadiene, linearhydroxy-terminated polybutadiene, and polycarbonate diol.
 31. Theformulation as defined in claim 28, wherein said polyol includeshydroxy-terminated polybutadiene, linear hydroxy-terminatedpolybutadiene, and polycarbonate diol.
 32. An actively modifiedpolymer-modified bitumen formulation comprising: 25-75 wt. % of a firstcomponent that consists of bitumen, coal tar, or combinations thereof;1-49 wt. % of a second component that consists of polyurethane, or blendof polyurethane and rubber, said polyurethane including isocyanate endgroups, said polyurethane formed from a polyisocyanate compound and apolyol, said polyol includes a molecular weight compound of 1000-5000molecular weight, a content of said polyol creating a NCO/OH equivalentratio of 2:1 to 15:1 in said bitumen formulation; wherein a weightpercent of said first component is greater than a weight percent of saidsecond component.